This invention relates to a vehicle motor switching apparatus for selecting a type of a vehicle motor among a series motor, a compound-wound motor and a shunt motor.
A vehicle motor is mostly driven by a battery installed in a vehicle, particularly an electric vehicle which has been developed or being free of petroleum dependence and being less polluting. Controllable of such a motor is one of the important factors in determining the vehicle performance.
The Japanese Utility Model Publication No. 1983(58)-21284 discloses such motor control. The control apparatus disclosed therein comprises a feeder circuit including a controller for adjusting a voltage or a current applied to a motor in response to an amount of depression of an accelerator.
Also, the apparatus comprises a brake circuit for braking the motor by short-circuiting two terminals of the motor and a switch interlocked by the accelerator for switching the two circuits.
The feeder circuit is driven to rotate the motor when the accelerator is depressed. On the other hand, the brake circuit is driven to brake the motor when the accelerator is released.
As is already known, a motor driven by means of a d.c. current from a battery is roughly classified into a series motor, a compound-wound motor and a shunt motor according to a wiring configuration of coils for exciting field poles.
Those motors are selectively used. However, only one type of motor is sometimes not sufficient for an electric vehicle which should be operated at various travelling conditions.
The series motor produces a large starting torque for excellent starting acceleration but also has a large speed variation and increases an engine speed greatly as load torque to the motor is made small.
On the other hand, the shunt motor has low speed variation or stable engine speed even if the load torque varies but also has relatively a small speed control region when a load is connected thereto.
Furthermore, the compound-wound motor has characteristics intermediate between the series motor and the shunt motor and a slow response to the change of the operating state.